Water Dispersible Clay Research Articles

Variation of Soils Erodibility in Mbe Agropastoral Area in Relation with Land Utilization, Central Cameroon

The study of the soils from Mbé and Wack is carried out in the framework of the knowledge of soils from the Adamawa Region of Cameroon and their erodibility was investigated using erodibility indices obtained through physico-chemical data. Eleven topsoils (0 - 20 cm) samples were collected on different land use and their susceptibility to erosion was assessed. The water dispersible clay (34.92 - 121.75 g•kg−1), the clay dispersion ratio (0.45 - 0.84) and the dispersion ratio (0.75 - 0.89) were high in the studied soils while the clay aggregation (13.16 - 42.27g•kg−1) and the clay flocculation index (0.16 - 0.55) were low to moderate indicating their high erodibility. The soils under natural vegetation, more clayey, displayed the highest amount of water dispersible clay while cropped soils recorded the smaller ones. Globally, in cropped soils, those under cereals displayed the highest clay dispersion indices than those under tubers. This suggests that tubers cropping practices in studied soils enhance their erodibility. Statistical analyses revealed that amorphous Al and Fe are elements which limit soils erodibility while K+ and promote soils particles dispersion. Sustainable management of these soils will consist on limiting runoff through agricultural practices such as direct seedling and orienting tillage perpendicularly to slope gradient.

우리나라 관개논에서 토양특성과 대형농기계를 사용한 경작년수에 따른 여름 강우기 분산성 점토의 함량

우리나라 관개논에서 토양특성과 대형농기계를 사용한 경작년수에 따른 여름 강우기 분산성 점토의 함량

Colloidal nitrogen is an important and highly-mobile form of nitrogen discharging into the Great Barrier Reef lagoon

Soil-borne colloids have been linked to long-distance transport of radionuclides, metal(loid)s and nutrients. Colloid-associated nitrogen (N) will have different mechanisms of biogeochemical cycling and potential for water-borne transport over longer distances compared to dissolved N. The role that colloids play in the supply and mobility of N within catchments discharging into the Great Barrier Reef (GBR) lagoon is unexplored. Here, we examine water-dispersible clay (WDC) from soil samples collected from gullies and agricultural drains within three different land uses (sugarcane, non-agricultural land and grazing) within the Townsville area. The proportion of soil N associated with WDC was inversely correlated with total soil N, with up to 45% of the total soil N being colloid-associated in low N gully soils. Within the <0.45 µm fraction of the WDC, only 17–25% of the N was truly dissolved (<3 kDa) at the gully sites compared to 58% in the sugarcane sites. Our results demonstrate the importance of colloidal N and the inaccuracy of assuming N < 0.45 µm is dissolved in the sampled areas, as well as providing an alternate explanation for the large amounts of what has previously been defined as dissolved inorganic N in runoff from non-fertilized grazing land. In particular, they describe why non-fertilized land uses can contribute significant N < 0.45 µm, and why catchment models of nutrient export based on soil N concentrations can over-estimate loads of particulate nitrogen derived from monitoring data (N > 0.45 µm). The findings suggest that managing soil erosion may also contribute to managing N < 0.45 µm.

Soil structure and soil organic matter in water-stable aggregates under different application rates of biochar

Soil structure and soil organic matter in water-stable aggregates under different application rates of biochar

Soil Physical Attributes and Organic Carbon in a Cohesive Yellow Latosol (Oxisol) Under Different Soil Management Systems in the Coastal Plains of Bahia, Brazil

Although soil physical attributes are determining factors of soil quality and for root development of crops, they are often neglected when dealing with soil management, which refers only to fertility. The objective of this work was to evaluate soil physical characteristics, organic carbon content and carbon stock levels in yellow Latosol cohesive distrophic coastal plains of Bahia, Brazil, where different soil management systems were implemented. Soil texture, water dispersible clay, flocculation index, soil density and porosity, liquid limit, plastic limit, plasticity index, stability of aggregates, organic carbon content and resistance to penetration were evaluated from soil samples collected in the 40 cm-top soil. The different soil plot covers consisted of (i) Eucalyptus with grasses (EGR), (ii) Eucalyptus with spontaneous vegetation (EVE), (iii) fallow (POU), (iv) pasture (PAS), and (v) native forest (MN). It was found that EVE and MN contributed to greater stability of larger aggregates in the 20-40 cm-soil layer compared to EGR, PAS and POU. The high organic matter contents of soils of the cultivated plots (EVE and EGR) increased the limits of consistency. Soil management systems with Eucalyptus and pasture contributed to accelerate the oxidation process and the loss of C.

Land use impact on clay dispersion/flocculation in irrigated and flooded vertisols from Northern Cameroon

Clay dispersion by water is important for soil and water conservation as well as for irrigation scheduling. In the present study, clay dispersion/flocculation of irrigated and flooded vertisols in North Cameroon was investigated using clay dispersion/stability indices. Nine vertisols topsoils (0–20 cm) samples were collected on different land use and their clay dispersion indices were assessed. Vertisols were acidic to slightly basic, with smectites as dominant clay mineral. The water dispersible clay (160–340 g kg−1), the dispersion ratio (0.55–0.79) and the clay dispersion ratio (0.48–0.83) were high in the studied vertisols while the clay flocculation index (0.17–0.54) and the clay aggregation (70–230 g kg−1) were low to moderate, indicating their high dispersion. Cropped vertisols displayed the higher amount of water dispersible clay while not cropped recorded the smaller amount. Concerning the cropped soils, irrigated vertisols displayed the highest clay dispersion indices suggesting that agricultural practices (irrigation) enhance clay dispersion. Globally, the clay dispersibility trend was: irrigated paddy ˃ rainy sorghum ˃ rainfed paddy ˃ dry-season sorghum ˃ not cropped. Statistical analyses revealed that amorphous Al, Na+ and electrical conductivity enhance clay dispersion while organic matter, nitrogen and Ca++ promote clay flocculation/aggregation. The overall findings emphasized that practices such as heavy tillage and irrigation induce clay dispersion. Minimum tillage, electrolytes concentration monitoring in irrigation water, irrigation scheduling based on soil moisture control, organic matter inputs and implementation of adapted dams are measures susceptible to limit their degradation through clay dispersion.

Physico-chemical attributes of a Cambisol under pasture managed with annual burns after sugarcane vinasse application

PurposeSugarcane vinasse is generated in large amounts and can be utilized to improve soil attributes, especially in areas degraded by burns. The aim of the present study was to evaluate the effects of sugarcane vinasse on physico-chemical attributes of a Cambisol managed via annual burns.MethodsSoil samples were collected from an annually burned area under pasture and used in an experiment in pots to evaluate the effects of dosages of vinasse (0, 18.8, 37.5, 56.3, 75.0, 112.5, and 150.0 m3 ha−1) on water-dispersible clay, {text{pH}}_{{{text{H}}_{2} {text{O}}}}, organic matter, K+, Ca2+ + Mg2+, and K+/(Ca2+ + Mg2+).ResultsThe results showed that vinasse application reduces water-dispersible clay, does not alter {text{pH}}_{{{text{H}}_{2} {text{O}}}}, and increases organic matter, K+, Ca2+ + Mg2+, and K+/(Ca2+ + Mg2+). The water-dispersible clay was reduced by the formation of bonds with organic matter, which overlapped the repulsive forces intensified by the increment of K+/(Ca2+ + Mg2+). The estimated vinasse dosage that provided the minimum water-dispersible clay (69 g kg−1) was 110 m3 ha−1.ConclusionsVinasse can be applied to improve the physico-chemical attributes of soils degraded by annual burns.

Improvement of degraded physical attributes of a saline-sodic soil as influenced by phytoremediation and soil conditioners

ABSTRACTThis study aimed to evaluate the use of phytoremediation and soil conditioners in the recovery of physical attributes of a saline-sodic Fluvic Neossol in Brazil Northeast. The applied treatments were: Atriplex nummularia L., as phytoremediation plant, due to its ability to extract salts from the soil; organic conditioners, such as bovine and sheep manure; gypsum and polymer, as chemical conditioners. Samples with preserved structure were collected at the time of the experiment installation and 18 months after in the layers 0–10 cm and 10–30 cm. The analyzed attributes were: water dispersed clay, dispersion index, bulk density, penetration resistance, soil porosity, and saturated hydraulic conductivity. The use of sheep manure, gypsum and polymer promoted an increase in saturated hydraulic conductivity in the 0–10 cm layer from 4.51 to 16.37 cm day−1, 11.26 to 23.95 cm day−1 and 7.24 to 22.77 cm day−1, respectively. Gypsum increased the macroporosity in the superficial layer by 42.6%. Atriplex and polymer were more efficient at reducing soil penetration resistance. The polymer was more efficient at improving the physical properties. However, it is necessary to consider phytoremediation with Atriplex as a more sustainable alternative that can still be used as complementary fodder in animal feed.

Physicochemical and Structural Properties of an Oxisol under the Addition of Straw and Lime

Core Ideas Liming represents a common agricultural practice for abating soil acidity. High doses of lime on the Oxisol surface increases the electronegativity of the soil system. High electronegativity increases clay dispersion in the uppermost soil layer. Clay migration led to a series of physical alterations in soil subsurface layers. Overliming can lead to the degradation of highly weathered soil structures. Liming represents a common agricultural practice for abating soil acidity. Nevertheless, elevated amounts of agricultural lime in Oxisols, with or without cultural residue addition, could alter soil physicochemical properties and impact soil structure. In this context, the physical, chemical, and structural behaviors of an Oxisol under the addition of lime and straw were assessed. Lime doses (0, 3.9, 7.8, and 15.6 Mg ha–1) were either applied on the surface or incorporated into the 0‐ to 5‐cm soil layer. Straw applications followed the same procedure with quantities of 0, 4, 12, or 16 Mg ha–1. The effects on the soil profile were evaluated through physicochemical (specific surface area, ζ potential, and pH), physical (density, penetration resistance, water dispersible clay, and total porosity), and micromorphological properties (surface area, volume, connectivity, size, and pore anisotropy) 1 yr after soil incubation in polyvinyl chloride cylinders 30 cm long and 14.5 cm in diameter. Lime application on the surface or into the 0‐ to 5‐cm layer increased soil pH to values above 7.0 and the electronegative potential of soil colloid surface, promoting clay dispersion. Water‐dispersed clay migrated in the soil profile, causing pore obstruction, and higher soil density and penetration resistance. In addition, excessive lime decreased specific surface area, anisotropy degree and the connectivity of the soil pore system. Straw addition promoted a slight increase of colloids electronegative potential but did not alter soil physical properties.

Effects of anabolic and catabolic nutrients on woody plant encroachment after long-term experimental fertilization in a South African savanna.

The causes of the worldwide problem of encroachment of woody plants into grassy vegetation are elusive. The effects of soil nutrients on competition between herbaceous and woody plants in various landscapes are particularly poorly understood. A long-term experiment of 60 plots in a South African savanna, comprising annual applications of ammonium sulphate (146–1166 kg ha-1 yr-1) and superphosphate (233–466 kg ha-1 yr-1) over three decades, and subsequent passive protection over another three decades, during which indigenous trees encroached on different plots to extremely variable degrees, provided an opportunity to investigate relationships between soil properties and woody encroachment. All topsoils were analysed for pH, acidity, EC, water-dispersible clay, Na, Mg, K, Ca, P, S, C, N, NH4, NO3, B, Mn, Cu and Zn. Applications of ammonium sulphate (AS), but not superphosphate (SP), greatly constrained tree abundance relative to control plots. Differences between control plots and plots that had received maximal AS application were particularly marked (16.3 ± 5.7 versus 1.2 ± 0.8 trees per plot). Soil properties most affected by AS applications included pH (H2O) (control to maximal AS application: 6.4 ± 0.1 to 5.1 ± 0.2), pH (KCl) (5.5 ± 0.2 to 4.0 ± 0.1), acidity (0.7 ± 0.1 to 2.6 ± 0.3 cmol kg-1), acid saturation (8 ± 2 to 40 ± 5%), Mg (386 ± 25 to 143 ± 15 mg kg-1), Ca (1022 ± 180 to 322 ± 14 mg kg-1), Mn (314 ± 11 to 118 ± 9 mg kg-1), Cu (3.6 ± 0.3 to 2.3 ± 0.2 mg kg-1) and Zn (6.6 ± 0.4 to 3.7 ± 0.4 mg kg-1). Magnesium, B, Mn and Cu were identified using principal component analysis, boundary line analysis and Kruskal-Wallis rank sum tests as the nutrients most likely to be affecting tree abundance. The ratio Mn/Cu was most related to tree abundance across the experiment, supporting the hypothesis that competition between herbaceous and woody plants depends on the availability of anabolic relative to catabolic nutrients. These findings, based on more than six decades of experimentation, may have global significance for the theoretical understanding of changes in vegetation structure and thus the practical control of invasive woody plants.

Surface and incorporated liming effects on clay dispersion, water availability, and aeration capacity of a Dystrudept soil

ABSTRACT Liming represents a management procedure that can affect the soil structure and its thermodynamic processes. In this context, the aims of this study were to assess (i) the effects of the surface and incorporated liming on the clay dispersion, soil water availability, and aeration capacity; (ii) the influence of soil chemical alterations in its physical attributes. For this, a field experiment was installed in a family farming property, located in the southeastern region of the State of Parana, in a Dystrudept soil. The treatments were 3 application modes (on the surface, incorporated via plowing and incorporated via subsoiling and harrowing), with and without 15 Mg∙ha–1 of lime, aiming to increase the base saturation in the topsoil (0 – 0.20 m) to approximately 70%. Eighteen months after application, undisturbed and disturbed soil samples were collected from the 0 – 0.10 and 0.10 – 0.20 m layers to evaluate the waterdispersed clay (WDC), water content at the field capacity (θFC) and at the permanent wilting point (θPWP), plant available water capacity (PAWC), relative water capacity (RWC), aeration capacity (AC), granulometry and the soil structural and chemical attributes. WDC content in the 0 – 0.10 m layer increased when the soil was revolved and it was influenced exclusively when lime was applied on the soil surface. With surface liming there were increase in θFC, θPWP, PAWC and RWC, and reduction in AC in the 0 – 0.10 m layer. In the 0.10 – 0.20 m layer isolated effects were verified of the modes application and liming on θFC, PAWC and RWC, while θPWP was not influenced by treatments. The soil water availability and aeration capacity alterations were mainly affected by micro and macroporosity increases, pH reduction, Al3+ precipitation, and substitution of this ion in the exchange complex by Ca2+ and Mg2+.

Factors affecting clay dispersion in oxisols treated with vinasse

Vinasse is a potassium-rich waste generated in large amounts by the ethanol production that, applied in the soil, can promote changes in water dispersible clay and in its physical quality. The aim of this study was to evaluate the clay dispersion of Oxisols after vinasse application and correlate it with some chemical attributes. Samples were collected in two Oxisols (155 and 471 g of clay kg-1), put in pots, received dosages of vinasse (0, 50, 100, 150 and 200 m3 ha-1) and remained incubated during 120 days. Phosphorous, organic carbon, pH H2O, pH KCl, pH CaCl2, Al3+, H+Al3+, Ca2+, Mg2+, K+, Na+, Delta pH and the proportion between monovalent and bivalent cations have been evaluated and correlated with the clay flocculation degree. Vinasse changed almost all chemical variables in both soils and increased the flocculation in the sandy soil, but did not change the clayey one. Delta pH, Mg2+ and K+ significantly correlated with the flocculation degree in the sandy soil. It is possible to conclude that the dispersive effect of K+ added by vinasse are irrelevant, considering the flocculant effect caused by the increment in Mg2+ and Delta pH after vinasse application.

Application of various methodological approaches for assessment of soil micromorphology due to VESTA program applicable to prediction of the soil structures formation

Application of various methodological approaches for assessment of soil micromorphology due to VESTA program applicable to prediction of the soil structures formation

Poorly-crystalline components in aggregates from soils under different land use and parent material

Fe and Al compounds of low degree of crystallinity are important components for the development and conservation of soil structure in many soils. In this work, the influence of parent material and land use on the abundance of poorly-crystalline forms of Fe and Al was studied in six macroaggregate fractions from 28 soils. The soils selected are developed on two geological materials with very different composition: granites or amphibolites, and under two land uses: shrubland or agricultural. Poorly crystalline Fe and Al were extracted with oxalic acid–ammonium oxalate (inorganic and organic forms), and with pyrophosphate (organic forms). Soils developed on amphibolite were richer in organic matter and poorly-crystalline Fe and Al compounds than soils developed on granite. Agricultural soils were impoverished in organic carbon and organic-complexed Al with respect to shrubland soils, and enriched in inorganic poorly crystalline forms of Fe. The differences related to land use were more evident in the amphibolite soils. Aggregate stability, assessed by water-dispersible clay quantification, decreased in agricultural soils with respect to shrubland soils, in particular for those developed on amphibolite. This reduction of aggregate stability in agricultural soils is likely due to a combination of several processes: loss of organic matter, higher pH, and an overall loss of poorly-crystalline Fe and Al compounds, in particular Al-organic matter complexes.

Aggregates morphometry in a Latosol (Oxisol) under different soil management systems

Changes in soil physical properties are inherent in land use, mainly in superficial layers. Structural alterations can directly influence distribution, stability and especially morphometry of soil aggregates, which hence will affect pore system and the dynamic process of water and air in soil. Among the methods used to measure these changes, morphometry is a complementary tool to the classic methods. The aim of this study was to evaluate structural quality of a Latosol (Oxisol), under different management systems, using morphometric techniques. Treatments consisted of soil under no-tillage (NT); pasture (P), in which both had been cultivated for ten years, and an area under native vegetation (NV – Savannah like vegetation). Aggregates were sampled at depths of 0-0.10 and 0.10-0.20 m, retained on sieves with 9.52 – 4.76 mm, 4.76 – 1.0mm, 1.0 – 0.5mm diameter ranges. Aggregate morphometry was assessed by 2D images from scanner via QUANTPORO software. The analyzed variables were: area, perimeter, aspect, roughness, Ferret diameter and compactness. Moreover, disturbed samples were collected at the same depths to determine particle size, aggregate stability in water, water-dispersible clay, clay flocculation index and organic matter content. It was observed that different soil management systems have modified soil aggregate morphology as well as physical attributes; and management effects’ magnitude increased from NT to P.

Effect of humic substances and clay minerals on the hydrosorption capacity of clay particles in meadow soils (Middle Priamurje, Far East of Russia)

The study of clay fractions is usually focused on water-dispersible clay (WDC), which is a good indicator of many soil processes involving water (water erosion, transfer and removal of nutrients and contaminants). Aggregated clay (AC) that remains after WDC extraction is also important, as it controls the formation of aggregates and their mechanical and water resistance. The aim of this study was a gradual extraction of WDC and AC fractions from periodically overmoistening meadow podbel (mollic planosol) and the study of the content and composition of humic substances and clay minerals in these fractions as well as their effect on the hydrosorption capacity. The complete extraction of clay fractions showed that AC prevails over WDC along the entire profile and most evidently in the Ag horizon. Most of the organic matter is concentrated in AC. X-ray diffractometry and SEM analysis revealed a similar set of minerals in both fractions, but in different proportions. In the Ag and Elcg horizons, WDC is enriched with clastic components (fine-dispersed quartz, feldspars, amphiboles) and clay minerals with rigid structures (illite, kaolinite, chlorite), compared to AC. In the Btg1 horizon smectite prevails in both fractions. The specific surface, which characterizes the hydrosorption capacity of clays, of WDC is 28–95 m2/g less than that of AC. Maximal difference in specific surface of clays is found in the horizon Elcg, where AC has the highest content of free iron. The present study allowed defining the heterogeneity of the total clay in the periodically overmoistened meadow soil, which is manifested in differences in composition and properties of WDC and AC fractions. AC largely determines hydrosorption properties of soil due to a high content of organic matter and the predominance of swelling minerals in its composition, compared with WDC. The obtained data highlight the importance of studying clay fractions WDC and AC for the characteristics of differentiation and aggregation of the clay in soils.

Boundary between Soil and Saprolite in Alisols in the South of Brazil

Despite numerous studies conducted on the lower limit of soil and its contact with saprolite layers, a great deal of work is left to standardize identification and annotation of these variables in the field. In shallow soils, the appropriately noting these limits or contacts is essential for determining their behavior and potential use. The aims of this study were to identify and define the field contact and/or transition zone between soil and saprolite in profiles of an Alisol derived from fine sandstone and siltstone/claystone in subtropical southern Brazil and to subsequently validate the field observations through a multivariate analysis of laboratory analytical data. In the six Alisol profiles evaluated, the sequence of horizons found was A, Bt, C, and Cr, where C was considered part of the soil due to its pedogenetic structure, and Cr was considered saprolite due to its rock structure. The morphological properties that were determined in the field and that were different between the B and C horizons and the Cr layer were color, structure, texture, and fragments of saprolite. According to the test of means, the properties that support the inclusion of the C horizon as part of the soil are sand, clay, water-dispersible clay, silt/clay ratio, macroporosity, total porosity, resistance to penetration, cation exchange capacity, Fe extracted by DCB, Al, H+Al, and cation exchange capacity of clay. The properties that support the C horizon as a transition zone are silt, Ca, total organic C, and Fe extracted by ammonium oxalate. Discriminant analysis indicated differences among the three horizons evaluated.

Dispersion and flocculation of Vertisols, Alfisols and Oxisols in Southern Brazil

Incomplete soil dispersion in particle-size analysis reduces clay content and increases silt and sand contents, whereas abrasion affects size distribution by large particles' breakdown into smaller size-fractions. We evaluated different dispersion techniques on particle-size distribution in ten soil horizons of seven soils from southern Brazil, with varying soil texture, clay mineralogy and organic matter. We tested two contact times of chemical dispersant (sodium hydroxide 1M): immediate shaking and shaking after 12h of contact; three types of spheres: glass, technyl and nylon; five horizontal reciprocating shaking times (30, 60, 120, 240 and 480min); and standard method (electric mixer) with chemical dispersant (sodium hydroxide 1M), 12h of contact time, plus 15min of physical stirring at 12,000rpm. Soils with high contents of clay and iron oxides or exchangeable aluminum were less dispersible, respectively, because of organo-mineral complexes and aluminum affinity to organic matter and clay minerals. Soils with kaolinite and quartz and with low organic matter content in the B horizon were easily dispersible. Nylon spheres are adequate for physical dispersion, either immediately or 12h after addition of chemical dispersant. Horizontal shaking for 60 or 120min is sufficient for adequate dispersion of kaolinitic soils, while for soils of difficult dispersion, such as oxidic soils, 240min of horizontal shaking is necessary. For water dispersible clay, horizontal shaking during 240min is suggested. These results allow for standardizing the contact time of chemical dispersant, horizontal shaking timing, and sphere types, for soils with varying texture, clay mineralogy and organic matter, in laboratories working in tropical environments, with improved dispersion and time saving.

English

Soil and water losses were evaluated in dystrophic ultisol of the Cerrado-Pantanal Ecotone cropped with common bean, Phaseolus vulgaris L, under different tillage systems. The treatments studied were conventional tillage with primary and double secondary disking (CT), minimum tillage with chisel plow (MT) and no-tillage (NT) systems, the last associated to 4 crop densities: 0, 3, 6 and 9 Mg ha-1. In order to characterize the experimental area, analyzes of water-dispersible clay, flocculation degree, aggregate stability, soil bulk density, soil porosity, soil moisture and surface roughness was carried out. Using the portable rainfall simulator, the plots received application of rainfall of 60 mm h-1 to evaluate soil and water loss. The treatments were arranged in a randomized block design with four replications. The soil losses ranging from 11.38 to 380.56 × 10-3 kg m-2, while water losses ranging from 4.15 to 31.57 × 10-3 m3 m-2. The highest soil losses occur in CT and the lowest water losses in MT. In NT, the highest level of crop residue deposition on soil surface reduces soil and water loss. Compared to water loss, soil loss is more susceptible to variations in the type of tillage system and levels of plant residues. Key words: Water erosion, soil conservation, simulated rainfall.

Aggregation and clay dispersion of an oxisol treated with swine and poultry manures

Fertilisation using animal manure can improve soil structure. However, the positive and negative effects of this practice remain inconclusive, and manure application can change the superficial electric potential, thereby increasing the dispersible clay content, disaggregation and susceptibility of soil to erosion and contamination of surface water. The objective of this study was to evaluate a water-dispersible clay and the aggregation of an oxisol over time with the application of different doses of swine and poultry manure. The experiment was conducted in a very clayey dystroferric red latosol, and the treatments consisted of the superficial application of 33 and 66m3ha−1 swine manure and 1920 and 3840kgha−1 poultry manure for corn production. A treatment without fertiliser (mineral or organic) was used as a reference. Soil samples from 0.00 to 0.10m layer were collected at 0, 15, 30 and 60 days after manure application to determine the soil aggregate classes, weighted mean diameter (WMD), aggregate stability index, dispersible clay content, pHH2O and pHKCl. The ΔpH was also determined. The application of swine manure led to rapid and dynamic changes in the dispersible clay content as well as the aggregation process compared to the application of poultry manure. The effects of the application of 33 or 66m3ha−1 swine manure can be divided into three phases: (i) immediate increases in the pHH2O resulting in an increase in dispersible clay content and the mass of aggregates <0.250mm immediately after the application of the manure at 0 days after application (DAA); (ii) a decrease in the pHH2O as well as flocculation and restructuring of the soil between 15 and 30 DAA; and (iii) a further increase in the mass of aggregates <0.250mm between 30 and 60 DAA. In contrast to the swine manure applications, a cementation effect of organic carbon was observed in the poultry manure applications, and clay flocculation and soil aggregation occurred after the application of 1920kgha−1 or 3840kgha−1 poultry manure, thereby increasing the WMD at 15 DAA. However, the aggregation effect was ephemeral, and at 30 and 60 DAA, decreases in the WMD and aggregates >2.00mm were observed independent of the doses of applied poultry manure.